Bond polarity with hydrogen — which element forms the least polar H–X bond? Considering electronegativity differences, which element listed would form the least polar covalent bond with hydrogen in H–X?

Introduction / Context:
Bond polarity depends on the electronegativity difference between bonded atoms. Comparing several common elements reveals which H–X bond is closest to nonpolar, an idea that influences acidity, reactivity, and spectroscopy.

Given Data / Assumptions:

• Electronegativity increases across a period and decreases down a group.
• Approximate Pauling electronegativities: H about 2.20, P about 2.19, C about 2.55, N about 3.04, O about 3.44, F about 3.98.
• Least polar means the smallest electronegativity difference with hydrogen.

Concept / Approach:

Calculate qualitative differences: |P − H| is minimal, near zero, so H–P is close to nonpolar. |C − H| is modest, giving slightly polar bonds. Nitrogen, oxygen, and especially fluorine are much more electronegative than hydrogen, creating increasingly polar H–X bonds with significant bond dipoles.

Step-by-Step Solution:

Verification / Alternative check:

Chemical properties of phosphines support weak bond polarity in P–H, consistent with small electronegativity difference and characteristic reactivity compared to amines or alcohols.

Why Other Options Are Wrong:

Nitrogen and oxygen produce significantly polar N–H and O–H bonds. Carbon gives moderate polarity. Fluorine would make the most polar H–F bond among the listed choices.

Common Pitfalls:

Assuming bond polarity tracks atomic size rather than electronegativity; polarity depends primarily on electronegativity difference.

Final Answer:

Phosphorus